[Late diagnosis of cystinosis in 2 brothers: histological and ultrastructural renal study].

Cystinosis was discovered by chance in two adolescent boys who had proteinuria with minor tubular abnormalities. Renal biopsies were examined by light microscopy, electron microscopy and immunofluorescence. There were few histological changes but crystals were present in the epithelial cells of the glomerulus and occasionally in the tubules. A further unusual feature was the detection of IgA deposits in the mesangium.